International audienceIn this paper, an evaluation of transmit beamforming (TxBF) contribution is analyzed in the context of an indoor residential environment. Using an optimized 3D ray tracing tool, the multiple-input multiple-output (MIMO) propagation channel is simulated. The algorithm of singular value decomposition is applied and a new transmission scheme is considered. Comparisons of cases with/without TxBF are realized by analyzing the received power, the signal to noise ratio (íµí±†íµí±íµí±…) of each spatial stream and the channel capacity. It is shown that the TxBF capacity gain increases when the MIMO channel correlation at the transmit side reaches high values, especially when only the dominant eigen mode is selected. The main result concerns the antenna spacing: a judicious choice of the transmitting antenna spacing can improve the effective transmission range by more than 45% in non-line of sight (NLOS) conditions. Several MIMO configurations (number of antennas and spatial streams) are also compared to determine the relevance of a possible activation of TxBF. The interference influence is studied and it is shown that under some conditions, TxBF improves the signal to interference ratio (SIR)

International audienceIEEE 802.11n standard came as a rescue; the existing standards are increasingly seen as inadequate since applications become more complex and require more bandwidth. Several techniques have been put into operation to meet two basic requirements: significantly greater bit rate and radio coverage. However, studies have shown that the theoretical limit in terms of throughput is far from being reached and that the received power does not explain the performance degradation. A list of suspect parameters is analyzed in this paper to assess their effect on performance of the IEEE 802.11n physical layer taken as an application of MIMO technology in indoor context. It is shown that for values of angular spread below 27°, the data rate cannot exceed 117 Mbps and the antennas spacing can compensate the performance degradation caused by other parameters. Results are given in terms of correlation coefficient, other channel characteristics and the packet error rate